Effect of Particle Size Distribution on Chain Structures in Magnetorheological Fluids

Magnetorheological fluids (MRFs) consist of carbonyl iron powders suspended in a carrier fluid. Prior simulation work has typically modeled MRFs as consisting of spherical particles having a uniform radius. In this study, we use particles whose radii are represented as a log-normal distribution, and investigate what effect the standard deviation of the distribution has on fluid properties and particle microstructure through large-scale (high particle count) numerical simulations. We find that for even for narrow particle size distributions, the particle size distribution has a substantial effect in that it dramatically alters chain structures and substantially reduces fluid stress at low Mason numbers. Thus, the particle size distribution must be correctly modeled in order to accurately simulate chain structures in MRFs.